In certain communication systems (e.g. OFDM systems, etc.), a “probe” symbol is transmitted by a first station to a second station. Such “probe” symbol is typically an OFDM symbol with known pilots at each subcarrier. In use, the second station uses the received OFDM symbol for channel estimation and coefficient generation for a pre-equalizer located in the first station. Each coefficient of the pre-equalizer is associated with a distinct subcarrier. Unfortunately, a variety of noise often corrupts such OFDM symbols which, in turn, corrupts coefficient generation and subsequent data transfer.
Prior art FIG. 1 is frequency domain illustration 100 of an OFDM symbol 102 that is affected by ingress noise 104, in accordance with the prior art. Such upstream ingress noise 104, when present, occupies a subset of the subcarriers of the OFDM symbol 102. Typically, the ingress noise 104 affects the same subcarriers in all related OFDM symbols. Further, as mentioned earlier, the presence of the ingress noise 104 on a subcarrier corrupts the computed value of the pre-equalizer coefficient for that subcarrier. Unfortunately, the second station that receives the OFDM symbols 102 has no knowledge about the presence of the ingress noise 104 and which subcarriers of the OFDM symbols 102 are affected.
Prior art FIG. 2 is a time domain illustration 200 of an OFDM symbol 202 that is affected by burst noise 204, in accordance with the prior art. Such burst noise 204, when present, affects all the subcarriers of the OFDM symbol 202, corrupting the pre-equalizer coefficient for all the subcarriers. The burst noise 204 affects one or two (successive) OFDM symbols. Unfortunately, similar to the ingress noise 104, the second station that receives the OFDM symbol has no knowledge about the presence of the burst noise 202 in the OFDM symbols 202.
There is thus a need for addressing these and/or other issues associated with the prior art.